The present invention concerns non-A, non-B hepatitis (hereinafter called NANB hepatitis) virus genome, polynucleotides, polypeptides, related antigen, antibody and detection systems for detecting NANB antigens or antibodies.
Viral hepatitis of which DNA and RNA of the causative viruses have been elucidated, and their diagnosis and even prevention in some have been established, are hepatitis A and hepatitis B. The general name NANB hepatitis was given to the other forms of vital hepatitis.
Post-transfusion hepatitis was remarkably reduced after introduction of diagnostic systems for screening hepatitis B in transfusion bloods. However, there are still an estimated 280,000 annual cases of post-transfusion hepatitis caused by NANB hepatitis in Japan.
NANB hepatitis viruses were recently named C,D and E according to their types, and scientists started a world wide effort to conduct research for the causative viruses and subsequent extermination of the causative viruses.
In 1988, Chiron Corp. claimed that they had succeeded in cloning RNA virus genome, which they termed hepatitis C virus (hereinafter called HCV), as the causative agent of NANB hepatitis and reported on its nucleotide sequence (British Patent 2,212,511 which is the equivalent of European Patent Application 0,318,216). HCV (C100-3) antibody detection systems based on the sequence are now being introduced for screening of transfusion bloods and for diagnosis of patients in Japan and in many other countries. The detection systems for the C100-3 antibody have proven their partial association with NANB hepatitis; however, they capture only about 70% of carriers and chronic hepatitis patients, or they fail to detect the antibody in acute phase infection, thus leaving problems yet to be solved even after development of the C100-3 antibody by Chiron Corp.
The course of NANB hepatitis is troublesome and most patients are considered to become carriers, then to develop chronic hepatitis. In addition, most patients with chronic hepatitis develop liver cirrhosis, then hepatocellular carcinoma. It is therefore very imperative to isolate the virus itself and to develop effective diagnostic reagents enabling earlier diagnosis.
The presence of a number of NANB hepatitis which cannot be diagnosed by Chiron's C100-3 antibody detection kits suggests a possibility of a difference in subtype between Chiron's HCV and Japanese NANB hepatitis virus.
In order to develop NANB hepatitis diagnostic kits of more specificity and to develop effective vaccines, it becomes an absolutely important task to analyze each subtype of NANB hepatitis causative virus at its genetic and corresponding amino acid level.